1. Field of the Invention
The present invention relates generally to the field of insulators and switches, and more particularly to a support arrangement for an insulator including a non-metallic element of suitable conductivity to permit the flow of leakage current as well as capacitive charging current through the element.
2. Description of the Related Art
Various rotatable insulators and insulating support columns are known in the field of electrical power distribution and transmission. For example, see U.S. Pat. Nos. 4,596,906 and 4,752,859 and co-pending application Ser. No. 07/331,216 now U.S. Pat. No. 4,983,792.
In such arrangements, the top of the insulator carries a conductor at one potential and the bottom of the insulator is rotatably supported with respect to a support surface at a second potential. Even where the insulator is fabricated from a polymeric material, it is desirable to provide a low friction interface between the insulator and the support surface to minimize operating forces and to avoid wearing of the insulator. Such wear could detract from the proper alignment of the insulator. Additionally, for outdoor use, the harsh environment makes it impractical to lubricate the surfaces. Thus, it is desirable to utilize a bearing, which may also be referred to as a bushing. While a metallic bearing may be utilized, polymeric materials offer lower frictional characteristics and no corrosion effects. However,, if a bearing of polymeric material is utilized, sufficient voltage may be developed across the bearing such that the resulting leakage currents and capacitive charging currents can cause tracking across and/or deterioration of the bearing.